10/02/2026
Blood pooling is one of the most overlooked connections between hEDS, POTS, and MCAS.
When you have hypermobile Ehlers-Danlos Syndrome, your connective tissue is lax — and that includes the walls of your veins. Healthy veins are elastic and contract to push blood back up toward your heart.
When that tissue is loose, blood pools in the legs and abdomen instead of circulating properly. Your heart rate then spikes to compensate, which is a hallmark of POTS.
On top of that, mast cells — which are heavily concentrated in connective tissue — become dysregulated, triggering the cascade of reactions we know as MCAS. Three diagnoses, one root cause. This is why so many of us don’t just have one condition — we have all three.
